The Complete Illustrated Encyclopaedia of Boating.
I got this with my boat and it looked really old and a bit tattered so I put it away and only now had a look at it.
It is a really interesting read!
Wrote in 1977 by Alan Lucas of the Cruising guides fame it is an A to Z of boating and nautical terms with over 1000 illustrations.

Not sure why photos are on the side...?
Like "Sandbagger" was an early kind of racing boat which used sandbags for ballast, I never heard of that.
Or "Soldiers Wind" is a beam wind, being the easiest course on which to steer a boat so that "even a soldier" could do it!
Great for the newbie or experienced yachtie alike and perfect for reference or just to while away a few hours and maybe discuss over a few rums...
There's still a couple available on eBay for $10 plus.
cheers